Flexible imaging member seam treatment article and preparation method thereof

ABSTRACT

A flexible imaging belt seam treatment article comprising a high-temperature-resistant flexible substrate that supports a thermoplastic polymer film. The film is deposited on the flexible substrate by dissolution of a film-forming thermoplastic polymer in a carrier solvent, applying the resulting solution to the flexible substrate, and eliminating the carrier solvent. The article can then be used to treat a seam of a flexible imaging belt by placing it on the seam, heating the strip and seam, and applying pressure to the strip and seam.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to U.S. patent application Ser. No.10/063,971 (Attorney Docket No. D/A2002), entitled IMPROVED FLEXIBLEIMAGING MEMBER SEAM TREATMENT, U.S. patent application Ser. No.10/063,972 (Attorney Docket No. D/A2002Q), entitled FLEXIBLE IMAGINGMEMBER SEAM TREATMENT APPARATUS, and U.S. patent application Ser. No.______ (Attorney Docket No. D/A2002Q2), entitled FLEXIBLE IMAGING MEMBERSEAM TREATMENT APPARATUS, all filed on May 30, 2002 herewith, thedisclosures of which are hereby incorporated by reference in theirentirety. In addition, this application is related to U.S. patentapplication Ser. No. 09/428,932, filed on Oct. 28, 1999 in the names ofYu et al. and entitled SEAM STRESS RELEASE AND PROTRUSIONS ELIMINATIONPROCESS, (Attorney Docket No. D/96182Q3), the entire disclosure of whichis incorporated herein by reference.

BACKGROUND AND SUMMARY

[0002] 1. Field of the Invention

[0003] Embodiments generally relate to a seam morphological improvementapproach, and, more specifically, to a post ultrasonically-welded seamovercoat treatment for flexible imaging member belts.

[0004] 2. Background and Summary

[0005] Flexible electrostatographic belt imaging members are well knownin the art. Typical electrostatographic flexible belt imaging membersinclude, for example, photoreceptors for electrophotographic imagingsystems, electroreceptors such as ionographic imaging members forelectrographic imaging systems, and intermediate image transfer beltsfor transferring toner images in electrophotographic and electrographicimaging systems. These belts are usually formed by cutting arectangular, a square, or a parallelogram shape sheet from a webcontaining at least one layer of thermoplastic polymeric material,overlapping opposite ends of the sheet, and joining the overlapped endstogether to form a welded seam. The seam extends from one edge of thebelt to the opposite edge. Generally, these belts comprise at least asupporting substrate layer and at least one imaging layer comprisingthermoplastic polymeric matrix material. The imaging layer as employedherein is defined as and refers to any of the dielectric imaging layerof an electroreceptor belt, the transfer layer of an intermediatetransfer belt, and the charge transport layer of an electrophotographicbelt. Thus, the thermoplastic polymeric matrix material in the imaginglayer is generally located in the upper portion of a cross section of anelectrostatographic imaging member belt, the substrate layer being inthe lower portion of the cross section of the electrostatographicimaging member belt. Although the flexible belts of interest include thementioned types, for simplicity reasons, the discussion hereinafter willbe focus on the electrophotographic imaging member belts.

[0006] Between the substrate and imaging layers, such flexibleelectrophotographic imaging members or multilayered photoreceptors alsotypically include an electrically conductive layer, an optional holeblocking layer, an adhesive layer, a charge generating layer, and, insome embodiments, an anti-curl backing layer. One type of multilayeredphotoreceptor comprises a layer of finely divided particles of aphotoconductive inorganic compound dispersed in an electricallyinsulating organic resin binder to form a layer that is chargegenerating and charge transporting. A typical layered photoreceptorhaving separate charge generating (photogenerating) and charge transportlayers is described in U.S. Pat. No. 4,265,990, the entire disclosurethereof being incorporated herein by reference. In negatively-chargedvarieties of such photoreceptors, a charge generating layer is capableof photogenerating holes and injecting the photogenerated holes into thecharge transport layer.

[0007] Although excellent toner images can be obtained with multilayeredbelt photoreceptors, it has been found that as more advanced, higherspeed electrophotographic copiers, duplicators and printers aredeveloped, fatigue-induced cracking of the charge transport layer at thewelded seam area is frequently encountered during photoreceptor beltcycling. Moreover, the onset of seam cracking has also been found torapidly lead to seam delamination due to fatigue, shortening beltservice life. Dynamic fatigue seam cracking can possibly happen inionographic imaging member belts as well.

[0008] As mentioned above, flexible electrostatographic imaging membersare typically fabricated from a sheet cut from an imaging member web,generally in a rectangular or parallelogram shape, and a sheet is formedinto a belt by joining overlapping opposite marginal end regions of thesheet. A seam is typically produced in the overlapping marginal endregions at the point of joining. Joining can be effected by any suitablemeans, such as by welding (including ultrasonic), gluing, taping,pressure heat fusing, and the like. Ultrasonic welding is generally thepreferred method of joining because it is rapid, clean (no solvents),and produces a thin and narrow seam. In addition, ultrasonic welding ispreferred because the mechanical pounding of the welding horn causesgeneration of heat at the contiguous overlapping end marginal regions ofthe sheet to maximize melting of one or more layers therein. A typicalultrasonic welding process is carried out by holding down the overlappedends of a flexible imaging member sheet with vacuum against a flat anvilsurface and guiding the flat end of an ultrasonic vibrating horntransversely across the width of the sheet, over and along the length ofthe overlapped ends, to form a welded seam.

[0009] When ultrasonically welded into a belt, the seam of multilayeredelectrophotographic imaging flexible members can occasionally containundesirable high protrusions such as peaks, ridges, spikes, and mounds.These seam protrusions present problems during image cycling of the beltmachine because they interact with cleaning blades to cause blade wearand tear, which ultimately affects cleaning blade efficiency and servicelife. Moreover, the protrusion high spots in the seam can also interferewith the operation of subsystems of copiers, printers and duplicators bydamaging electrode wires used in development subsystems that positionthe wires parallel to and closely spaced from the outer imaging surfaceof belt photoreceptors. These closely spaced wires are employed tofacilitate the formation of a toner powder cloud at a development zoneadjacent to a toner donor roll and the imaging surface of the beltimaging member. Another frequently observed mechanical failure in theimaging belts during image cycling is that, after being subjected toextended bending and flexing cycles over small diameter belt supportrollers, the ultrasonically welded seam of an electrophotographicimaging member can develop cracks that propagate and lead todelamination of the belt. Addtionally, such cracking and delaminationcan result from lateral forces caused by mechanical rubbing contactagainst stationary web edge guides of a belt support module duringcycling. Seam cracking and delamination is further aggravated when thebelt is employed in electrophotographic imaging systems utilizing bladecleaning devices and some operational imaging subsystems. Alteration ofmaterials in the various photoreceptor belt layers such as theconductive layer, hole blocking layer, adhesive layer, charge generatinglayer, and/or charge transport layer to suppress cracking anddelamination problems is not easily accomplished. The alteration of thematerials can adversely impact the overall physical, electrical,mechanical, and other properties of the belt such as well as coatinglayer uniformity, residual voltage, background, dark decay, flexibility,and the like.

[0010] As mentioned above, when a flexible imaging member used in anelectrophotographic machine is a photoreceptor belt fabricated byultrasonic welding of overlapped opposite ends of a sheet, theultrasonic energy transmitted to the overlapped ends melts thethermoplastic sheet components in the overlap region to form a seam. Theultrasonic welded seam of a multilayered photoreceptor belt isrelatively brittle and low in strength and toughness. The joiningtechniques, particularly the welding process, can result in theformation of a splashing that projects out from either side of the seamin the overlap region of the belt. The overlap region and splashings oneach side of the overlap region comprise a strip from one edge of thebelt to the other that is referred herein as the seam region. The seamregion of a typical overlap seamed flexible belt is about 1.6 timesthicker than the thickness of the body of the belt. Because of thesplashing, a typical flexible imaging member seamed belt has a peaksplashing height of about 76 micrometers above the surface of theimaging layer at the junction between the top splashing and the surfaceof the belt. The junction meeting point is the undesirable site ofphysical discontinuity which has been found to act as a stressconcentration point that facilitates early onset of seamcracking/delamination under the dynamic fatigue-inducing conditions towhich imaging members are subjected in normal use.

[0011] The photoreceptor belt in an electrophotographic imagingapparatus undergoes bending strain as the belt is cycled over aplurality of support and drive rollers. The excessive thickness of thephotoreceptor belt in the seam region due to the presence of thesplashing results in a large induced bending strain as the seam travelsover each roller. Generally, small diameter support rollers are highlydesirable for simple, reliable copy paper stripping systems inelectrophotographic imaging apparatus utilizing a photoreceptor beltsystem operating in a very confined space. Unfortunately, small diameterrollers, e.g., less than about 0.75 inch (19 millimeters) in diameter,raise the threshold of mechanical performance criteria to such a highlevel that photoreceptor belt seam failure can become unacceptable formultilayered belt photoreceptors. For example, when bending over a 19millimeter diameter roller, a typical photoreceptor belt seam splashingcan develop a 0.96 percent tensile strain due to bending. This is 1.63times greater than a 0.59 percent induced bending strain that developswithin the rest of the photoreceptor belt. Therefore, the 0.96 percenttensile strain in the seam splashing region of the belt represents a 63percent increase in stress placed upon the seam splashing region of thebelt.

[0012] Under dynamic fatiguing conditions, the seam provides a focalpoint for stress concentration and becomes the point of crack initiationwhich is further developed into seam delamination causing prematuremechanical failure in the belt. Thus, the splashing tends to shorten themechanical life of the seam and service life of the flexible memberbelts used in copiers, duplicators, and printers.

[0013] Although a solution to suppress the seam cracking/delaminationproblems has been successfully demonstrated, as described in a priorart, by a specific heat treatment process of a flexibleelectrophotographic imaging member belt with its seam parked directly ontop of a 19 mm diameter back support rod for releasing treatment at atemperature slightly above the glass transition temperature (T_(g)) ofthe charge transport layer of the imaging member, nevertheless this seamstress release process was also found to produce various undesirableeffects such as causing seam area imaging member set and development ofbelt ripples in the active electrophotographic imaging zones of the belt(e.g., the region beyond about 25.2 millimeters from either side fromthe midpoint of the seam). Moreover, the heat treatment can induceundesirable circumferential shrinkage of the imaging belt. The set inthe seam area of an imaging member mechanically adversely interacts withthe cleaning blade and impacts cleaning efficiency. The ripples in theimaging member belt manifest themselves as copy printout defects.Further, the heat induced imaging belt dimensional shrinkage alters theprecise dimensional specifications required for the belt. Another keyshortcoming associated with the prior art seam stress release heattreatment process is the extensive heat exposure of a large seam area.This extensive heat exposure heats both the seam area of the belt aswell as the rod supporting the seam. Since the belt must be cooled tobelow the glass transition temperature of the thermoplastic material inthe belt prior to removal from the support rod to produce the desireddegree of seam stress release in each belt, the heat treatment andcooling cycle time is unduly long and leads to very high belt productioncosts. Additionally, such seam heat treatment stress-release processingdoes not produce the desired seam surface smoothing and protrusion spotelimination.

[0014] Since there is no effective way to prevent the generation oflocalized high protrusions at the seam, imaging member belts areinspected, right after seam welding belt production process, manually byhand wearing a cotton glove through passing the index finger over theentire seam length and belts found catching the glove by the protrusionsare identified as production rejects. Both the time consuming procedureof manual inspection and the number of seamed belts rejected due to thepresence of high seam protrusions constitute a substantial financialburden on the production cost of imaging members.

[0015] The following references may be of interest: U.S. Pat. No.5,190,608, issued Mar. 2, 1993 to Darcy et al., discloses a flexiblebelt having an outwardly facing surface, a welded seam having irregularprotrusion on the outwardly facing surface and a thin flexible striplaminated and covering the welded seam and protrusions. This belt can befabricated by providing a flexible belt having an outwardly facingsurface and a welded seam having irregular protrusions on the outwardlyfacing surface and laminating a thin flexible strip to the welded seam.The belt can be used in an electrostatographic imaging process.

[0016] U.S. Pat. No. 5,549,999, issued Aug. 27, 1996 to Swain et al.,discloses a process for coating flexible belt seams including providinga flexible belt having an outwardly facing surface and a welded seam,forming a smooth liquid coating comprising a hardenable film formingpolymer on the welded seam, the coating being substantially free offugitive solvent, and hardening the coating to form a smooth solidcoating on the seam.

[0017] U.S. Pat. No. 5,582,949, issued Dec. 10, 1996 to Bigelow et al.,discloses a process for coating flexible belt seams including providinga flexible belt having an outwardly facing surface and a welded seam,forming a smooth liquid coating on the welded seam, the liquid coatingcomprising a film forming polymer and a fugitive liquid carrier in whichthe belt surface is substantially insoluble, and removing the fugitiveliquid carrier to form a smooth solid coating on the seam.

[0018] U.S. Pat. No. 6,328,922 B1, issued Dec. 11, 2001 to Mishra etal., discloses a process for post treatment of an imaging member beltincluding providing a support member having a smooth flat surface,proving a flexible belt having a welded seam, supporting the innersurface of the seam on the smooth flat surface, contacting the seam witha heated surface, heating the seam region with the heated surface toraise the temperature in the seam region to a temperature of from about2° C. to 20° C. about the T_(g) of the thermoplastic polymer material,and compressing the seam with the heated surface with sufficientcompression pressure to smooth out the seam.

[0019] U.S. Pat. No. 5,552,005, issued Sep. 3, 1996 to Mammino et al.,discloses a flexible imaging sheet and a method of constructing aflexible imaging sheet. The method of constructing a flexible imagingsheet comprises overlapping, joining, and shaping first and secondmarginal end regions of a sheet to form an overlap region and anon-overlap region joined to one another by a seam in the overlap regionwith a generally planar surface co-planar with a surface of thenon-overlap region. The first and second marginal end regions aresecured to one another in the overlap region by the seam, and aresubstantially co-planar to minimize stress on the flexible imagingsheet. Minimization of stress concentration, resulting from dynamicbending of the flexible imaging sheet during cycling over a rollerwithin an electrophotographic imaging apparatus, is particularlyaccomplished in the present invention.

[0020] U.S. Pat. No. 6,074,504 to Yu et al., issued Jun. 13, 2000,discloses a process for treating a seamed flexible electrostatographicimaging belt including providing an imaging belt having two paralleledges, the belt comprising at least one layer comprising a thermoplasticpolymer matrix and a seam extending from one edge of the belt to theother, the seam having an imaginary centerline, providing an elongatedsupport member having at arcuate supporting surface and mass, thearcuate surface having at least a substantially semicircular crosssection having a radius of curvature of between about 9.5 millimetersand about 50 millimeters, supporting the seam on the arcuate surfacewith the region of the belt adjacent each side of the seam conforming tothe arcuate supporting surface of the support member, preciselytraversing the length of the seam from one edge of the belt to the otherwith thermal energy radiation having a narrow Gaussian wavelengthdistribution of between about 10.4 micrometers and about 11.2micrometers emitted from a carbon dioxide laser, the thermal energyradiation forming a spot straddling the seam during traverse, the spothaving a width of between about 3 millimeters and about 25 millimetersmeasured in a direction perpendicular to the imaginary centerline of theseam, and rapidly quenching the seam by thermal conduction of heat fromthe seam to the mass of the support member to a temperature below theglass transition temperature of the polymer matrix while the region ofthe belt adjacent each side of the seam conforms to the arcuatesupporting surface of the support member.

[0021] While these and other innovative prior art approaches providedimproved flexible belt seam morphology, nevertheless it has been foundthat solution of one problem has also created new undesirable issues.For example, overcoating the seam of a photoreceptor belt with metallicfoil can cause electrical seam arcing as the belt cycles beneath acharging device during electrophotographic imaging processes.Additionally, application of liquid overcoating layer over the seaminduced charge transport molecule crystallization in the vicinity of theseam overcoat, not to mention that liquid overcoating layer can producepoor adhesion bond strength to the seam after solidification into adried coat. Thus, there is a continuing need for electrostatographicimaging belts having improved welded seam design that is resistant toseam cracking/delamination, substantially free of seam protrusions, hasimproved seam region physical continuity, and is substantially free offactors that damage imaging subsystems.

[0022] Furthermore, there is an urgent need to provide seamed flexibleimaging belts with an improved seam morphology which can withstandgreater dynamic fatigue conditions thereby extending belt service life.It is also important, from the imaging member belt production point ofview, that effective cutting of unit manufacturing cost of seamedimaging belts can be realized if an innovative post seaming treatmentprocess can be developed and adopted for belt finishing implementationto provide the improvement of morphological seam surface smoothing freeof protrusion spots and to effect the elimination of physicaldiscontinuity at the junction meeting point where the top seam splashingmaking contact with the belt surface.

[0023] Embodiments of the instant invention provide such an improvedelectrostatographic imaging member that substantially overcomes theabove-noted deficiencies by providing a morphologically improved seamedelectrostatographic imaging member. Embodiments yield an improvedelectrostatographic imaging member with an ultrasonically welded seamwhich, after being subjected to post processing, exhibits greaterresistance to onset of dynamic fatigue induced seamcracking/delamination problem. After being subjected to post processingaccording to embodiments, seams exhibit good circumferential dimensiontolerance, robust mechanical seam function, and reduced cleaning bladewear. Seams treated according to embodiments are substantially free ofseam protrusions, have smoother surface morphological profiles, havelittle or no seam region physical discontinuity, and have reduced seamarea thickness that greatly reduces seam region bending stress when theelectrostatographic imaging member flexes over small-diameter beltmodule support rollers.

[0024] These results are achieved according to embodiments by, forexample, providing a flexible imaging member seam treatment articlepreparation method comprising providing a flexible substrate comprisinga high-temperature-resistant material, coating a surface of the flexiblesubstrate with a solution including at least one thermoplastic polymercomponent, and drying the coated surface to form a film of the at leastone polymer component on the coated surface. Where the substrate islarger than the size to be applied, the method can additionally comprisecutting the coated flexible substrate into at least one strip sized tocover the seam. Providing a flexible substrate can comprise providing aweb of a high-temperature-resistant material, and the method can furthercomprise forming a roll from the dried, coated flexible substrate, so asto form a tape reel. The flexible substrate can comprise a metallicsubstrate, a high-glass-transistion-temperature flexible polymeric film,such as a biaxially-oriented PET film. Coating a surface of the flexiblesubstrate can comprise providing a solution including a charge transportcompound, which can include dissolving a polycarbonate, such asMakrolon, and the charge transport compound in an organic solvent.

[0025] Such results can also be achieved according to embodiments by,for example, providing a belt seam treatment strip preparation methodcomprising dissolving a thermoplastic polymer into a solvent, applyingthe dissolved thermoplastic polymer to a surface of ahigh-temperature-resistant flexible substrate, and eliminating thesolvent to form a thermoplastic polymer film on the surface of thesubstrate. Dissolving a thermoplastic polymer into a solvent cancomprise providing an organic solvent, the thermoplastic polymerincluding at least one of a granular and a powder of a film-formingthermoplastic polymer. Eliminating the solvent can comprise air dryingthe coated substrate, baking the coated substrate, or any other suitablemethod. Applying the dissolved thermoplastic polymer can compriseproviding a web of high-temperature-resistant flexible substrate ontowhich the dissolved thermoplastic polymer is applied, which flexiblesubstrate can be a high-glass-transition-temperature flexible polymersubstrate, such as a biaxially-oriented PET film, or a metallic film.Dissolving a thermoplastic polymer can comprise providing a chargetransport compound, such asN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, andcan comprise providing a bisphenol-A polycarbonate of Makrolon.

[0026] Such results can further be achieved according to embodiments by,for example, providing a flexible imaging belt seam treatment articlecomprising a high-temperature-resistant flexible substrate supporting athermoplastic polymer film deposited thereon by dissolution of afilm-forming thermoplastic polymer in a carrier solvent, application ofa resulting solution to the flexible substrate, and elimination of thecarrier solvent. The high-temperature-resistant flexible substrate cancomprise a flexible metallic film, a high-glass-transition-temperaturepolymer sheet, or any other suitable flexible substrate material. Thedeposited thermoplastic polymer film can comprise, for example, abisphenol-A polycarbonate, such as Makrolon, and a charge transportcompound, such asN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine.

[0027] Although this invention deals with the seam overcoat materialformulations, it also relates to apparatus and lamination process foreffective flexible electrostatographic imaging member belts seamovercoating application, the following will focus only on seamedflexible electrophotographic imaging member belts to simplifydiscussion.

[0028] A more complete understanding of the process and apparatus of thepresent invention can be obtained by reference to the accompanyingdrawings wherein:

BRIEF DESCRIPTION OF DRAWINGS

[0029] In the detailed description, reference is made to theaccompanying drawings, in which:

[0030]FIG. 1 illustrates a schematic partial cross-sectional view of amultiple layered flexible sheet of electrophotographic imaging membermaterial with opposite ends overlapped.

[0031]FIG. 2 shows a schematic partial cross-sectional view of amultiple layered seamed flexible electrophotographic imaging member beltderived from the sheet illustrated in FIG. 1 after ultrasonic seamwelding.

[0032]FIG. 3 illustrates a schematic partial cross-sectional view of amultiple layered seamed flexible electrophotographic imaging member beltwhich has mechanical failure due to fatigue induced seamcracking/delamination problem.

[0033]FIG. 4 shows the cross sectional side view of a strip laminatorconsisting of a thin thermoplastic polymer laminate lightly adheringover a flexible carrier backing substrate layer readily for use ininvention seam overcoating application.

[0034]FIG. 5 is a schematic sectional side view of a seamed flexibleelectrophotographic imaging member belt in which the seam is held downonto the flat supporting surface of an elongated support member, with astrip laminator (not shown) positioned directly over the seam, whilesubjected to an elevated temperature seam overcoating/laminationprocess, utilizing a flat surfaced narrow heating and compression bar.

[0035]FIG. 6 shows an isometric, schematic view of a seamed flexibleelectrophotographic imaging member belt in which the seam is parked on,with a strip laminator placed directly over the seam, and held on a flatsurface of an elongated support member while subjected to an alternativeseam overcoating/lamination process, utilizing a hot rolling compressionwheel.

[0036]FIG. 7 is an isometric schematic view of a seamed flexibleelectrophotographic imaging member belt in which the seam is parked onand held against the arcuate convex surface of an elongated supportmember by vacuum, while heating with a focus infrared red spot andcoupled with a compressiom rolling wheel, is subjected to the heatingand compression processing of the present invention to yield seamovercoating/lamination and stress-release results.

[0037]FIG. 8 illustrates the schematic, sectional side view of the seamovercoating/lamination processing arrangement of FIG. 7, but with theonly exception that this exemplary embodiment used instead a CO₂ laserheat radiation source to replace the IR heating source shown in FIG. 7for achieving the very same invention result.

[0038]FIG. 9 shows the isometric, schematic view of a seamed flexibleelectrophotographic imaging member belt in which the seam is parked onand held over the arcuate convex surface of an elongated support memberby vacuum while subjected to another invention variance seamovercoating/lamination processing, utilizing a hot rolling compressionwheel. In the drawings and the following below, it is to be understoodthat like numeric designations refer to components of like function.

DETAILED DESCRIPTION

[0039] Although specific terms are used in the following description forthe sake of clarity, these terms are intended to refer only to theexemplary embodiment selected for illustration in the drawings, and arenot intended to define or limit the scope of invention.

[0040] Referring to FIG. 1, there is illustrated a flexibleelectrophotographic imaging member 10 in the form of a belt formed froma sheet having a first end marginal region 12 overlapping a second endmarginal region 14 to form an overlap region ready for a seam formingoperation. The flexible electrophotographic member 10 can be used withinan electrophotographic imaging device and can be a single film substratemember or a member having a film substrate layer combined with one ormore additional coating layers. At least one of the coating layerscomprises a film forming binder.

[0041] The flexible electrophotographic imaging member 10 can be asingle layer or comprise multiple layers. If the flexibleelectrophotographic imaging member 10 is to be a negatively chargedphotoreceptor device, the flexible electrophotographic imaging member 10may comprise a charge generator layer sandwiched between a conductivesurface and a charge transport layer. Alternatively, if the flexibleimaging member 10 is to be a positively charged photoreceptor device,the flexible imaging member 10 may comprise a charge transport layersandwiched between a conductive surface and a charge generator layer.

[0042] The layers of the flexible electrophotographic imaging member 10can comprise numerous suitable materials having suitable mechanicalproperties. Examples of typical layers are described in U.S. Pat. No.4,786,570, U.S. Pat. No. 4,937,117, and U.S. Pat. No. 5,021,309, theentire disclosures of which are incorporated herein by reference. Theflexible electrophotographic imaging member 10 of embodiments shown inFIG. 1 comprises, from top to bottom, a charge transport layer 16, agenerator layer 1, an interface layer 20, a blocking layer 22, aconductive ground plane layer 24, a supporting layer 26, and ananti-curl back coating layer 28. It should be understood that thethicknesses of the layers are conventional and that a wide range ofthicknesses can be used for each of the layers.

[0043] The end marginal regions 12 and 14 can be joined by any suitablemeans including gluing, taping, stapling, pressure and heat fusing toform a continuous member such as a belt, sleeve, or cylinder. However,for ease of belt fabrication, short operation cycle time, and themechanical strength of the fabricated joint, embodiments employ anultrasonic welding process to join the end marginal regions 12 and 14into a seam 30 in the overlap region, as shown in FIG. 2, to form aseamed flexible electrophotographic imaging member 10 in the form of abelt. In the ultrasonic seam welding process, ultrasonic energy appliedto the overlap region is used to melt suitable layers such as the chargetransport layer 16, generator layer 18, interface layer 20, blockinglayer 22, part of the support layer 26 and/or anti-curl back coatinglayer 28. Direct fusing of the support layer achieves optimum seamstrength.

[0044] Upon completion of welding the overlap region of the flexibleelectrophotographic imaging member sheet into a seam 30 using ultrasonicseam welding technique, the overlap region is transformed into anoverlapping and abutting region as illustrated in FIGS. 2 and 3. Withinthe overlapping and abutting region, the portions of the flexibleelectrophotographic imaging member 10, which once formed the endmarginal regions 12 and 14, are joined by the seam 30 such that the onceend marginal regions 12 and 14 are overlapping and abutting one another.The seam 30, indicated by a dashed line in FIG. 2, comprises twovertical portions joined by a horizontal portion. The midpoint of seam30 can be represented by an imaginary centerline extending the length ofseam 30 from one edge of belt 10 to the opposite edge, the imaginarycenterline (not shown) running along the middle of the horizontalportion which joins the two vertical portions illustrated in FIG. 2. Inother words, a plan view (not shown) of the horizontal portion of seam30 would show a strip much like a two lane highway in which thecenterline would be represented by the white divider line separating thetwo lanes, the two lanes comprising end marginal regions 12 and 14. Theflexible electrophotographic imaging member 10 has a first majorexterior surface or side 32 and a second major exterior surface or side34 on the opposite side. The seam 30 joins the flexibleelectrophotographic imaging member 10 so that, the bottom surface 34 atand/or near the first end marginal region 12 is integral with the topsurface 32 at and/or near the second end marginal region 14. Generally,the bottom surface 34 includes at least one layer immediately above thebottom of the belt in the first end marginal region 12, and the topsurface 32 includes including at east one layer immediately below thetop of the belt in the second end marginal region 14.

[0045] The welded seam 30 in embodiments also contains upper and lowersplashings 68 and 70 at each end thereof as illustrated in FIGS. 2 and4. The splashings 68 and 70 are formed in the process of joining the endmarginal regions 12 and 14 together when molten material is necessarilyejected from either side of the overlap region to facilitate directsupport-layer-to-support-layer fusing. The upper splashing 68 is formedand positioned above the overlapping end marginal region 14, abuttingthe top surface 32 and adjacent to and abutting the overlapping endmarginal region 12. The lower splashing 70 is formed and positionedbelow the overlapping end marginal region 12, abutting bottom surface 34and adjacent to and abutting the overlapping end marginal region 14. Thesplashings 68 and 70 extend beyond the sides and the edges of the seam30 in the overlap region of the welded flexible electrophotographicimaging member 10. The extension of the splashings 68 and 70 beyond thesides and the edges of the seam 30 is undesirable for many machines suchas electrophotographic copiers, duplicators, and other such machinesthat require precise edge positioning of a flexible electrophotographicimaging member 10 during machine operation. Generally, the extension ofthe splashings 68 and 70 at the belt edges of the flexibleelectrophotographic imaging member 10 are removed by a notchingoperation.

[0046] A typical upper splashing 68 has a height or thickness t of about90 micrometers and projects about 17 microns above the surface of theoverlapping end marginal region 12. Each of the splashings 68 and 70 hasan uneven, but generally rectangular, shape including one side 72, afree side that forms a free end, extending inwardly toward top surface32 from an outwardly facing side 74, which extends substantiallyparallel to either the top surface 32 or the bottom surface 34. The freeside 72 of the splashing 68 forms an approximately perpendicular angleθ₁ with the bottom surface 34 of the flexible electrophotographicimaging member 10 at a junction 76. Likewise, the free side 72 of thesplashing 70 forms an approximately perpendicular angle θ₂ at a junction78 of the free side 72 of the lower splashing 70 and the bottom surface34 of the flexible imaging member 10. Both junctions 76 and 78 createfocal points for stress concentration and become initial points offailure affecting the mechanical integrity of the flexibleelectrophotographic imaging member 10.

[0047] During machine operation, the seamed flexible electrophotographicimaging member 10 cycles or bends over rollers, particularly smalldiameter rollers, of a belt support module within an electrophotographicimaging apparatus. As a result of dynamic bending/flexing of theflexible electrophotographic imaging member 10 during cycling, therollers repeatedly exert a force on the flexible imaging member 10 thatcauses large stresses to develop generally adjacent to the seam 30 dueto the excessive thickness and material discontinuity thereof. Thestress concentrations that are induced by bending near the junctionpoints 76 and 78 can reach values much larger than the average value ofthe stress over the entire length of the flexible electrophotographicimaging member 10. The induced bending stress is inversely related tothe diameters of a roller that the flexible imaging member 10 bends overand directly related to the thickness of the seam 30 of the flexibleelectrophotographic imaging member belt 10. When a structural member,such as the flexible electrophotographic imaging member 10, contains asudden increase in cross-sectional thickness at the overlap region, highlocalized stress occurs near the discontinuity, e.g. junction points 76and 78.

[0048] When the flexible electrophotographic imaging member 10 bendsover the rollers of a belt module within an electrophotographic imagingapparatus, the bottom surface 34 of the flexible electrophotographicimaging member 10, which is adapted to contact the exterior surface ofthe roller, is compressed. In contrast, the top surface 32 is stretchedunder tension. This is attributable to the fact that the top surface 32and bottom surface 34 move in a circular path about the circular roller.Since the top surface 32 is at greater radial distance from the centerof the circular roller than the bottom surface 34, the top surface 32must travel a greater distance than the bottom surface 34 in the sametime period. Therefore, the top surface 32 must be stretched undertension relative to a generally central portion of the flexibleelectrophotographic imaging member 10 (the portion of the flexibleelectrophotographic imaging member 10 generally extending along thecenter of gravity of the flexible imaging member 10). Likewise, thebottom surface 34 must be compressed relative to the generally centralportion of the flexible imaging member 10 (the portion of the flexibleelectrophotographic imaging member 10 generally extending along thecenter of gravity of the flexible electrophotographic imaging member10). Consequently, the bending stress at the junction point 76 will betension stress, and the bending stress at the junction point 78 will becompression stress.

[0049] Compression stresses, such as at the junction point 78, rarelycause seam 30 failure. Tension stresses, such as at junction point 76,however, are much more of a problem. The tension stress concentration atthe junction point 76 in great likelihood will eventually result incrack initiation through the electrically active layers of the flexibleelectrophotographic imaging member 10 as illustrated in FIG. 3. Theillustrated crack 80 is adjacent to the top splashing 68 of the secondend marginal region 14 of the flexible electrophotographic imagingmember 10. The generally vertically extending crack 80 initiated in thecharge transport layer 16 continues to propagate through the generatorlayer 18. Inevitably, the crack 80 extends generally horizontally todevelop seam delamination 81 which is propagated through the relativelyweak adhesion bond between the adjoining surfaces of the generator layer18 and the interface layer 20.

[0050] The formation of the local seam delamination 81 is typicallycalled seam puffing. The excess thickness of the splashing 68 and stressconcentration at the junction 76 causes the flexible electrophotographicimaging member 10 to perform, during extended machine operation, asthough a material defect existed therein. Thus, the splashing 68 tendsto promote the development of dynamic fatigue failure of the seam 30 andcan lead to separation of the joined end marginal regions 12 and 14severing the flexible imaging member 10. Consequently, the service lifeof the flexible imaging member 10 is shortened.

[0051] In addition to seam failure, the crack 80 acts as a depositorysite and collects toner, paper fibers, dirt, debris, and other unwantedmaterials during electrophotographic imaging and cleaning of theflexible electrophotographic imaging member 10. For example, during thecleaning process, a cleaning instrument, such as a cleaning blade, willrepeatedly pass over the crack 80. As the site of the crack 80 becomesfilled with debris, the cleaning instrument dislodges at least someportion of this highly concentrated level of debris from the crack 80.The amount of the debris, however, is beyond the removal capacity of thecleaning instrument, and portions of the highly concentrated debris aredeposited onto the surface of the flexible electrophotographic imagingmember 10. In effect, the cleaning instrument spreads the debris acrossthe surface of the flexible electrophotographic imaging member 10instead of removing the debris therefrom.

[0052] In addition to seam failure and debris spreading, the portion ofthe flexible member 10 above the seam delamination 81, in effect,becomes a flap which moves upwardly. The upward movement of the flappresents an additional problem during the cleaning operation. The flapbecomes an obstacle in the path of the cleaning instrument as theinstrument travels across the surface of the flexibleelectrophotographic imaging member 10. The cleaning instrumenteventually strikes the flap when the flap extends upwardly. As thecleaning instrument strikes the flap, great force is exerted on thecleaning instrument which can lead to damage thereof, e.g., excessivewear and tearing of the cleaning blade.

[0053] In addition to damaging the cleaning blade, the striking of theflap by the cleaning instrument causes unwanted vibration in theflexible electrophotographic imaging member 10. This unwanted vibrationadversely affects the copy/print quality produced by the flexibleelectrophotographic imaging member 10. The copy/print is affectedbecause imaging occurs on one part of the flexible imaging member 10simultaneously with the cleaning of another part of the flexible imagingmember 10.

[0054] To overcome the problems associated with seam cracking anddelamination, embodiments employ a seam treatment article, treatmentstrip, or laminator strip 32 applied in a strip to the seam region in aparticular fashion. A laminator strip 32 according to embodiments,shown, for example, in cross-section in FIG. 4, comprises a film or thinlaminate 34 adhering to a flexible backing substrate layer 36.Embodiments employ a thickness of the laminate 34 of between about 5micrometers and about 50 micrometers; particularly, good results can beachieved with a thickness of between about 10 micrometers and about 30micrometers.

[0055] Laminate 34 is a film-forming thermoplastic polymer that, inembodiments, is substantially identical or substantially compatible with(compatible means it can form polymer blend) the polymer binder of thecharge transport layer of the flexible imaging member. In this context,compatible means that the thermoplastic polymer film 34 can form apolymer blend with the polymer binder of the charge transport layer.Alternatively, embodiments can employ a laminate 34 that is a polymerblend of the polymer binder and a film-forming thermoplastic polymer. Inaddition, the laminate 34 of embodiments can contain organic chargetransport molecule of the same kind or of a different kind as that ofthe charge transport layer. The laminate 34 of embodiments can have awidth of from about 2 mm to about 15 mm, but can yield better resultswith a width of between about 3 and about 10 mm. The laminate 34 must becompressible and malleable under the heat and compression processingconditions to enable bonding to the seam and facilitate filling thephysical discontinuities of the seam.

[0056] Although the flexible backing substrate layer 36 can be ametallic foil or a high glass transition temperature (T_(g)) flexiblepolymer substrate, use of a polymer substrate that is substantially notaffected by the heat and compression of embodiments is preferred.Materials such as polyethylene terephthalate (PET, also known as Mylar),polyethylene naphthalate (Kadelex), polyimide (Kapton), and the likemeet such requirements and can be used in embodiments. A thickness ofbetween about 2 mils and about 5 mils is satisfactory in embodiments,and a width equal to the width of the laminate can be employed, witheven better seam overcoating/lamination results achieved in embodimentshaving a substrate about 2 to about 5 mm wider on each side of thelaminate 34. The laminate 34 preferably has, in embodiments, an 180°adhesion peel strength over the backing substrate layer 36 of betweenabout 3 g/cm and about 8 g/cm to ensure that the substrate can bereadily stripped off of the overcoat after completion of the treatmentprocess. Although in embodiments the laminator strip 32 is preferred tobe a dual-layer strip as illustrated in FIG. 4, it can also be just asingle laminate layer 34 if desired.

[0057] An apparatus for carrying out embodiments of the treatment methodincludes a heat source or heating means that heats the seam region (thearea of the imaging member 10 around the seam 30) after the laminate hasbeen placed in contact with the seam. Embodiments also include means forapplying pressure to the heated region. In embodiments, as shown in FIG.5, a hot compression bar or plate 145 is the heat source and provideslocalized heating and compression of the region about the seam 30,directly over which a laminator strip (not shown) has been placed, toyield seam overcoating/lamination result. Embodiments also include meansto hold the seam region in place during treatment, such as a vacuumsystem. Thus, while the seam 30 of imaging member 10 is positioned andvacuum held down on the flat smooth supporting surface of support member138, the heat source heats the seam region and strip. The hotcompression bar 145, preferably metallic, has a smooth outer contactingsurface that is coated with a thin abhesive or low surface energycoating to prevent imaging layer material and the laminator strip fromadhering to its surface when seam overcoating/lamination processing iscarried out. Any suitable abhesive or low surface energy material can beemployed, including fluoropolymers, such as Teflon, silicone, polyimide,and the like. A thin Teflon coating on the smooth contacting surface ispreferred in embodiments because it promotes ease of release andprevents imaging member material from sticking to the surface of theheating/compression bar 145 when making compression contact during seamlamination processing treatment. The efficiency of heat energy deliveryfrom the heating/compression bar 145, preferably comprising resistanceelements (not shown) temperature control, to the laminator strip andseam area during contact is adjusted by any suitable device, such as aconventional adjustable variac 132, to provide sufficient power to raisethe temperature of the laminator strip and seam area from about 20° C.to 70° C. above the T_(g) of the thermoplastic polymer material in thecharge transport layer (T_(g) of the laminate if it is lower than thatof the charge transport layer) of the electrophotographic imaging member10. This thermoplastic polymer material is the top layer of the imagingmember, which is for example the charge transport layer comprising apolymer binder with dissolved or molecularly dispersed charge transportcompound, of electrophotographic imaging member. Conventionalthermostats can be employed to regulate the temperature of theheating/compression bar 145A narrow vacuum channel 140 can be used inembodiments on each side of the support member to vacuum hold the belt10 down against the flat supporting surface of support member 138. Thevacuum channels 140 can be about 25 millimeters apart and extend, oneach side of seam 30, along the support member 138 to about the fullwidth of the belt 10. Suitable widths for the vacuum channels can beabout 60 mils (1.5 mm). The upper ends of the vacuum channels 140 areopen, and the lower ends are connected by a suitable device, such as avalved flexible hose (not shown), leading to any suitable vacuum source.After belt 10 is placed onto support member 138, such as manually or byany suitable conventional robotic device, the initially closed valve onthe flexible hose to the vacuum source is opened, enabling the device tosuck the belt 10 against the upper, flat, smooth surface of supportmember 138. This suction holds the belt 10 substantially immobile onsupport member 138 during seam overcoating/lamination processing. Ifdesired, embodiments can include a plurality of holes of any suitableshape (e.g. round, oval, square, and the like) instead of or in additionto the channels 140. The number and size of the holes should besufficient to hold the belt 10 against the support member. The size ofthe channels and holes should be small enough to avoid distortion of thebelt during the seam area heating and compression process. Theresistance of the belt to distortion when suction is applied depends onthe beam strength of the specific belt employed, which in turn dependsupon the specific materials in and thickness of the layers in the belt10. The support member 138 may comprise any suitable hard material.Typical materials include, for example, hard plastic, having a smoothand polished surface. Preferably, support member 138 is metallic.

[0058] In embodiments, the heating/compression bar 145 preferably has awidth of between about 6 millimeters and about 30 millimeters with alength sufficient to cover the seam 30 along the entire width of theimaging member 10. In the process, heating/compression bar 145compresses against laminator strip and seam 30 to make intimate forcecontact with the seam. Such intimate force contact made byheating/compression bar 145 substantially instantaneously elevates thetemperature of a small localized region of the imaging layer adjacent toseam 30 of the imaging member containing thermoplastic polymer. Thissmall localized region of the imaging layer in the upper portion of theseam region is heated substantially instantly above the T_(g) of thethermoplastic polymer. Typically, the T_(g) of a film forming polymerused for an electrophotographic imaging layer, e.g., the chargetransport layer, is at least about 45° C. to satisfy most imaging beltmachine operating conditions. The imaging layer of an imaging member isa charge transport layer if the imaging member is an electrophotographicimaging member and a dielectric layer if the imaging member is anelectrographic imaging member. Since the charge transport layer ofembodiments is a composite comprising a polymer binder, a dissolved ormolecularly dispersed charge transport organic compound, and optionalpigment particles, the T_(g) in this case is a T_(g) of the combination.Thus, the expression polymer material as employed herein is defined asthe polymer and any other material present in an imaging layer or in thelaminate. Such polymer materials used for electrophotographic imaginglayer coating applications normally have a T_(g) of at least about 45°C. to satisfy most imaging belt machine operating conditions.Preferably, the seam area heating and compression process is carried outbetween about 20° C. and about 70° C. above the T_(g) of thethermoplastic polymer material of the imaging layer (e.g., chargetransport layer) or the laminate (whichever one has the lower T_(g)) inorder to yield strong overcoated laminate adhesion bonding onto the seamregion, surface smoothing result, good physical continuity transition atthe seam region, and seam region thickness reduction outcome. Occurrenceof material melting, distortion, or cutting through of the seamcomponents during heat/compression processing treatment should beavoided, because this weakens or damages the belt.

[0059] For processing a flexible imaging member having a skewed seam,the belt itself can be cocked and adjusted such that the seam ispositioned, without skewing, on the flat support member 138 and underthe heating/compression bar 145.Compression bar 145 contacts andcompresses the laminator strip and seam 30 while the belt 10 is helddown against the flat supporting surface of the support member 138 bythe vacuum channels 140. During pressure contact, the heat conductionfrom the hot compression bar 145 heats up the seam region to thedesirable temperature and the compression pressure generated by the barfacilitates the bonding of the laminate to the seam to provide surfacesmoothing, eliminate or minimize seam region physical discontinuity, aswell as reduce seam region thickness. The compression bar 145 preferablyexerts a compressive pressure of between about 70 lbs/in² (5 kg/cm²) andabout 770 lbs/in² (55 kg/cm²) on the laminator strip and seam region inorder to achieve the invention seam overcoating/lamination result. Aneffective temperature range used for heat treating/laminating anovercoat onto the seam of a typical flexible photoreceptor belt,comprising a top exposed charge transport layer containing athermoplastic polycarbonate polymer and a dissolved or molecularlydispersed charge transport compound, is appropriately selected to be ina range of between about 85° C. (185° F.) and about 97° C. (206° F.);based on the fact that the charge transport layer with a thickness ofabout 24 micrometers has a T_(g) of about 82° C. (180° F.). Since thepreferred imaging member seam lamination treatment embodiment of thisinvention involves heat and pressure contact with only the seam region(a small surface area), the desired lamination treatment temperature isreadily reached and cooling of the heat treated seam region to roomambient is quickly attained, the entire overcoating/laminationprocessing is completed within a short cycle time. Generally, the cycletime of the seam overcoating/lamination processing for the typicalphotoreceptor belt can be accomplished in less than about 20 secondswith the process of this invention for belts having a width of betweenabout 20 centimeters and about 60 centimeters.

[0060] An alternate heat source and pressure applying system usable inembodiments is illustrated in FIG. 6. A single heated, rotatablecompression wheel 150 is rolled over the laminator strip 32 and seam 30of belt 10, which is parked and held down by vacuum (not shown) on asmooth flat surface of support member 148. The geometry and design offlat support member 148 is identical to the support member 138 shown inFIG. 5. Compression wheel 150 can have a flat outer peripheral surfaceprofile that exerts straight line compression contact against the seamto smooth the exposed surface of seam 30, eliminate protrusions, andreduce the seam region thickness. The direction of the compression forcevector is perpendicular to the surface of the support member. The loweredge profile of the peripheral surface of wheel 150 is straight andsubstantially parallel to the smooth flat surface of the support member148 during seam treatment. This peripheral surface should be maintainedat a temperature sufficient to raise the temperature of thethermoplastic polymer material of the top layer, the imaging layer, ofthe belt seam to at least its glass transition temperature T_(g). Theperipheral surface of wheel 150 preferably has a thin coating surface ofabhesive material to prevent imaging layer material from adhering to theperipheral surface of wheel 150 during the seam overcoating/laminationprocess. Any suitable abhesive material can be used. Typical low surfaceenergy or abhesive materials include, for example, fluoropolymers, suchas Teflon, silicone, polyimide, and the like. The heated compressionwheel 150 is preferably metallic with a smooth peripheral surface.Heating of the wheel can be accomplished by any suitable device such as,for example, by an electromagnetic induction RF heating mechanism 152 togive the desired temperature when wheel 150 traverses the full width ofbelt 10 and over seam 30 to compress the seam. Alternatively, any othersuitable device, such as a resistance wire heating system 154 can beemployed to heat compression wheel 150. Where the resistance wire ispart of the wheel, any suitable electrical connection, such as sliprings 156, can be used to provide electrical energy to the resistancewires. Sufficient heat energy should be supplied to wheel 150 toadequately heat the peripheral surface thereof. Preferably, the hotrotatable compression wheel 150 is reciprocated and the support member148 carrying belt 10 remain stationary during the seam treatment.However, if desired, the support tube and belt can be moved and thewheel remains stationary or both can be reciprocated to achieve relativemotion with each other. Wheel 150 remains rotatable and exerts a linearcompression force of between about 1 lb/in. (0.18 kilograms/cm) andabout 20 lbs/in. (3.6 kilograms/cm) over the laminator strip and seamregion during any of the aforesaid seam treatment embodiments. Since theline force of compressive contact, generated by the continuous rollingwheel pressure action against the laminator strip 32 across the entirebelt width, at least matches or is greater than the width of strip 32 atthe site on the seam heated by the hot wheel 150, the compressive lineof force contact is perpendicular to the seam length and of infinitenumbers or continuum as the hot wheel rolls and traverses to effect fullseam overcoating/lamination.

[0061] Another heat source usable in embodiments includes infraredradiation sources. Embodiments can, for example, use incandescent lampsor high intensity discharge lamps as the heat source. Additionally,optics, such as, for example, reflectors, lenses, and filters, can beused to alter the character, path, and intensity of the output of suchinfrared radiation sources. An example of an infrared radiation heatsource arrangement usable in embodiments is illustrated in FIG. 7. Ahigh power tungsten halogen quartz bulb infrared (IR) is the heat source103, and provides localized, focused IR heating. Preferably, optics areemployed to create a small, substantially circular heat spot thatpreferably straddles the laminator strip 32 after the strip 32 is placedon the seam 30 of imaging member 10. The seam region is, for example,held down on a hollow support cylinder 90 at about the 12 o”clockposition. A free rotating compression wheel 108 follows the heat spot toprovide localized compression to the heated portions of the laminatorstrip 32 and the seam region of imaging member 10. The circular IR heatspot should have a diameter sufficient to cover, yet not to exceed, theentire width of the laminator strip 32 in order to impart an effectiveresult. In embodiments, this width can be between about 2 mm and about15 mm in spot diameter. Compression wheel 108, trailing right behind theIR heat spot, is biased against the laminator strip 32 (placed over theseam 30) by a spring 110 to provide the needed compression force. Boththe IR heat source 103 and compression wheel 108 are supported by anysuitable means 112 (partially shown), such as part of the frame of theprocessing device. An advantage of using a curved, convex surface is toprovide seam bending stress release; the processed seam obtainedaccording to embodiments employing such a curved surface can yield anenhanced seam cracking/delamination life extension result under normaloperating conditions.

[0062] As in the previous examples, a narrow vacuum channel 104 can beused in embodiments on each side of the hollow support cylinder 90 tohold the belt 10 down against the arcuate convex surface of cylinder 90.The vacuum channels 140 can be about 180° apart and extend axially alongeach side of cylinder 90. Suitable widths for the vacuum channels can beabout 60 mils (1.5 mm). One end of tube 90 is sealed (not shown) and theother is connected by a suitable device such as a valved flexible hose(not shown) to any suitable vacuum source. After belt 10 is placed ontothe tube 90, such as manually or by any suitable conventional roboticdevice, the initially closed valve on the flexible hose to the vacuumsource is opened, enabling the device to suck the belt 10 against theupper, arcuate, convex surface of tube 90 and to achieve a substantially180 degree wrapping of belt 10 around the upper, arcuate, convex surfaceof tube 90. plugs, seals, end-caps, or the like can be used to close theend openings of supporting tube 90 to ensure vacuum buildup. Thissuction holds the belt 10 substantially immobile on the tube 90 duringseam overcoating/lamination processing. If desired, embodiments caninclude a plurality of holes of any suitable shape (e.g. round, oval,square, and the like) instead of or in addition to the slots 104. Thenumber and size of the holes should be sufficient to hold the belt 10against the support member. The size of the slots and holes should besmall enough to avoid distortion of the belt during the seam areaheating and compression process. The resistance of the belt todistortion when suction is applied depends on the beam strength of thespecific belt employed, which in turn depends upon the specificmaterials in and thickness of the layers in the belt 10.

[0063] In embodiments, the supporting cylindrical tube 90 for imagingbelt 10 has an outer radius of curvature of, for example, between about9.5 millimeters and about 50 millimeters (i.e. diameter of curvature ofbetween about 19 millimeters and about 100 millimeters). When the radiusof curvature chosen for invention seam overcoating/lamination processingis less than about 9.5 millimeters (i.e. diameter of curvature of about19 millimeters), the beam rigidity of the electrophotographic imagingbelt will raise the belt 10 bending resistance so high that only a verysmall curvature can be achieved prior to carrying out the treatment.When the radius of curvature is greater than about 50 millimeters (i.e.diameter of curvature of about 100 micrometers), the seam stress-releaseis not fully realized because little or insignificant seam bendingstress-release in the imaging layer is obtained.

[0064] With reference again to FIG. 7, the electrophotographic imagingbelt 10 is positioned with belt seam 30 parked directly over supportingcylindrical tube 90, so that the arcuate convex surface of tube 90 is inintimate contact with the back surface of belt 10 with the top imagingsurface of belt 10 facing away from tube 90. If desired, to furtherassure intimate contact and conformance of the belt to the top convexsurface of the tube 90 (say for instance, the belt is making an 180°wrap around the tube), a slight belt tension can be applied to the belt10 by any suitable means such as, for example, by inserting a lightweight cylindrical tube of the same outer diameter as tube 90 inside thelower loop of belt 10 while the belt 10 is hanging from tube 90. Tube 90can be cantilevered by securing one end to a supporting wall or frame. Adesirable imaging member wrapped angle for the seam segment parking overthe back supporting cylindrical tube 90 should provide an arcuate convexarea at the seam region at least about as wide as the diameter of theheated substantially circular IR spot. It is preferred that the wrapangle encompassing the seam and region of the belt adjacent each side ofthe seam conforming to the arcuate convex supporting surface of thesupport member be between about 10° and about 180°. The material usedfor tube 90 must be very hard and nearly incompressible. It can be ofany suitable material, including, for example, metal, plastic,composites, and the like, but is preferably metallic. Although theimaging member 10 is shown to be held down against the convex uppersurface of the full circular support tube 90 in FIG. 7, the elongatedsupport member may alternatively have any other suitable shape such asan elongated half circle, an elongated partial circle, a bar having anarcuate convex surface on the side contacting the seam, and the like,provided the support member employed has an arcuate convex curve surfacesufficient to retain and hold down the entire length of the seam regionof the parked belt during seam overcoating/lamination processing.

[0065] The IR tungsten halogen quartz bulb 105 emits a dominant radiantwavelength of about 0.98 micrometer. Preferably, at least about 80percent of the radiation emitted by the tungsten halogen quartz bulb 105has a radiant wavelength of about 0.98 micrometer. A typical,commercially available, high powered IR tungsten halogen quartz bulb 105that can be used in heating source 103 is a Model 4085 infrared heatingbulb, available from Research, Inc., and comprises a 750 watt tungstenhalogen quartz bulb (750Q/CL, available from Research, Inc.) positionedat a focal point inside an aluminum hemiellipsoid shaped heat reflector106 similar to the schematic arrangement shown in FIG. 7. This IRheating bulb 105 has an adjustable energy output to give suitable IRheat spot temperature; for example, with heat flux densities to 650watts per square inch (1007 kilowatts per square meter) at a 6millimeter diameter focal point of the converging infrared energy. A 500watt tungsten halogen quartz bulb is also available form Research, Inc.,and other suitable bulbs could be obtained from other manufacturers.Bulb 105 is positioned inside an hemiellipsoid reflector 106 at thefocal point of the reflector so that all the reflected energy from bulb105 converges at another focal point outside of the reflector 106. Ifthe hemiellipsoid reflector were formed into a complete ellipsoid ratherthan half an ellipsoid, there would be two symmetrically positionedfocal points, one where the bulb 105 is located and the other where thereflected energy from the bulb 105 converges. The reflector can be madeof any suitable coated or uncoated material. Typical materials include,for example, uncoated aluminum, gold plated metal, stainless steel,silver, and the like. If desired, the reflector can contain openings tofacilitate the circulation of a cooling gas. An increase in the area ofthe openings in the reflector will reduce the amount of reflected energyfrom bulb 105 that converges at another focal point outside of thereflector 106. The distance between the reflector and the outer surfaceof the seam is adjusted by any suitable positioning device, such as, forexample, a conventional lead screw and ball device 88. Any othersuitable device, such as a rod fixed to a movable carriage and slidingcollar fitted with a set screw, the collar being secured to thereflector and slidable on the rod, can be used so long as a highintensity, substantially circular IR spot can be formed. The diameter ofthe spot is, for example, between about 2 millimeters and about 15millimeters and covers the entire width of the laminator strip 32. thishigh intensity focused circular IR spot substantially instantaneouslyelevates the temperature of only a small localized region, sufficientenough to cover the width of the laminator strip 32 and to exceed theglass transition temperature (T_(g)) of the charge transport layer inthe seam area or the laminate 34 of laminator strip 32. Typically, theT_(g) of a film forming polymer in the formulation used forelectrophotographic imaging layer coating applications is at least about45° C. to satisfy most imaging belt machine operating conditions.Preferably, the heat exposure spot in embodiments should be betweenabout the 20° C. and about 70° C. above the lower of the T_(g) of theimaging layer or the laminate 32 to achieve sufficient seamovercoating/lamination and stress release results.

[0066] the IR heating source 103 is moved substantially continuously orincrementally, along and above, the laminator strip 32 and the seam 30,by manually or automatically means, such as by any suitable horizontallyreciprocateable carriage system (not shown). Typical horizontallyreciprocateable carriage systems include, for example, ball screw, twoway acting air cylinder, lead screw and motor combination, belt or chaindrive slide system, and the like. A relative speed of movement betweenthe heating source/compression wheel assembly and the support tube 90holding the seamed belt 10 can be from about 1 centimeter to about 20centimeters per second with satisfactory results. A relative speedbetween about 2.5 centimeters and about 12.5 centimeters per secondyields better results. Alternatively, if desired, the whole integralpart of the IR heat source 103 with compression wheel assembly can beheld stationary while the tube 90 carrying the hold-down imaging membercan be set to motion, in exact but reversed manners as just described,to achieve the same processing outcome.

[0067] The rotatable compression wheel 108 illustrated in FIG. 7 canhave a peripheral surface with an arcuate, concave cross section with acurvature that substantially corresponds to or is slightly larger thanthe predetermined curvature of the arcuate, convex, substantiallysemicircular cross section of the elongated surface of the upper half ofthe support tube 90. The wheel 108 produces a compression line pressurecontact between the peripheral surface of the wheel and outer surface ofthe seam, augmented by tension force generated by spring 110. To produceeffective invention seam area overcoating/lamination result that canyield good seam region physical continuity and an improved surfacemorphological profile, it is important that the peripheral surface ofthe compression wheel has an arcuate concave radius of curvature.Preferably, the arcuate concave radius of curvature is between about 9.5millimeters and about 55 millimeters. The arcuate concave radius ofcurvature should correspond to or be slightly larger (e.g., by up toabout 10 percent larger) than the convex surface radius of curvature ofthe support tube 90, which preferably has a convex radius of curvatureof between about 9.5 millimeters and about 50 millimeters. The radius ofthe compression wheel 108, measured from its center of rotation or axisto the midpoint of line contact against the seam, can be, for example,between about ⅛ inch (3.2 millimeters) and about ½ inch (12.7millimeters), so long as the pressure application requirements ofembodiments are met. Measurement of the radius of the compression wheel108 is analogous to measuring the radius at the waist of an hour glass,the compression wheel 108 having a cross sectional shape (taken alongthe axis of the hour glass) similar to that of an hour glass.

[0068] Since the heated localized site cools very quickly, a very smallcompression wheel radius measured at the waist allows delivery of thecircular hot spot from the IR heat source 103 to the laminator strip(placed over the seam) closer to the imaginary axis of the wheel or theline of compression so that it is in tangential contact with waist ofthe wheel (e.g., bottom of the arcuate channel at about the 3 o”clockposition of the wheel when a vertically aligned compression wheel isemployed). Preferably, contact of the IR heat spot to the waist or anyother part of the wheel 108 is avoided to prevent heat build up in thewheel. By positioning the focus beam of the IR close to the waist of asmall radius wheel, the localized site heated by the IR heat spot isvery close to the line of compressive contact exerted by the compressionwheel against the laminator strip 32 from one side of the seam region tothe other which, therefore, allows quick compression force applicationby the wheel to the localized heated spot before this hot spot cools toa temperature below the T_(g) of heated polymer material in thelocalized site and thereby effecting seam overcoating/lamination result.However, the radius at the waist of the wheel should not be so smallthat rigidity of the compression wheel is compromised. Thus, forexample, the waist radius of the compression wheel should not be sosmall as to cause the wheel or wheel support member to bend when it isused to apply a compression force to the seam region. The limiting waistradius of the wheel 108 is strongly dependent on the specific materialsused to make the wheel. Similarly, bending resistance is also dependenton the specific materials selected for the wheel.

[0069] If desired, embodiments of the IR heat source 103 can be designedto have varying adjustable positions such that it can be tilted,inclined, or angled to allow positioning of the incident focused IR heatspot even closer to the line of compressive contact between thecompression wheel 108 and the laminator strip/seam region. Since theline of compressive contact generated by the rolling compression wheelcontacting the laminator strip/seam region is greater than or equal tothe laminator strip width, the lines of compressive contact forcegenerated are substantially perpendicular to the seam length and ofinfinite number. This achieves substantially complete seamovercoating/lamination processing with seam smoothing, stress-release,and substantial reduction of physical discontinuities of the entire seamregion. Therefore, it is preferable that the line of compressive contactmade by the compression wheel 108 on the laminator strip 32 form an arcof sufficient length to cover the full width of the laminator strip 32.The circumferential concave surface of the compression wheel 108preferably generates a uniform linear compression force of, for example,between about 1 lb/in (0.18 kilograms/cm) and about 20 lbs/in (3.6kilograms/cm) when in rolling contact with the laminator strip 32. Bycomparison, if a compression wheel 108 having a peripheral surface witha cross section having an infinite radius of curvature (which isessentially a straight line) is used, only point contact is achievedsince support member surface is arcuate. The compression wheel 108 canbe of any suitable material, including, for example, metallic, hardplastic, or composite materials having a smooth contacting surface. Itis preferred that the contacting surface comprises a thin coating of lowsurface energy material, such as a fluoropolymer, such as Teflon,polysiloxane, a polyimide, such as Kapton, and the like.

[0070] In the event that it is required to process a flexible imagingmember having a slanted seam (i.e. a seam that is an angle other than 90degrees with each edge of belt 10), the integral part of heating source103 and compression wheel assembly may be programmed or set to preciselytrack the seam when traversing the entire belt width. However, it ispreferred that the belt be cocked and adjusted so that the seam isparallel to an imaginary axis of the support cylinder member (i.e.,without skewing) along the top of the support cylinder member after beltmounting.

[0071] Although the IR heat source 103 is shown as a quartz halogen lampin FIG. 7, any other suitable source of heat energy can be used as theIR heat source 103. For example, embodiments can use an IR laser, suchas a sealed carbon dioxide (CO₂) laser, as the IR heat source 103, as isillustrated, for example, in FIG. 8. Sealed carbon dioxide (CO₂) lasersare commercially available, such as a Model Diamond 64 sealed carbondioxide laser from Coherent, Inc., which is a slab laser comprising apair of spaced apart, planar electrodes having opposed light reflectingsurfaces. The spacing of the electrodes is arranged such that light willbe guided in a plane perpendicular to the reflecting surfaces, whilelight in a plane parallel to the light reflecting surfaces is allowed topropagate in free space and is only confined by a resonator. Preferably,the lasing medium is a standard CO₂ lasing mixture, including, forexample, helium, nitrogen, and carbon dioxide with a 3:1:1 ratio, plusthe addition of five percent xenon. The gas is maintained between 50 and110 torr and preferably on the order of about 80 torr. The gas iselectrically excited by coupling a radio frequency generator between theelectrodes, as is explained in the description of a typical sealedcarbon dioxide laser found, for example, in U.S. Pat. No. 5,123,028, theentire disclosure of which is incorporated herein by reference. Sealedcarbon dioxide lasers are also described in U.S. Pat. No. 5,353,297,U.S. Pat. No. 5,353,297, and U.S. Pat. No. 5,578,227, the entiredisclosures of which are also incorporated herein by reference. Whilesuch sealed carbon dioxide lasers can produce, for example, a 150 wattbeam, when used in embodiments, such lasers should be adjusted todeliver a lower output of, for example, about 6 watts for the seam heattreatment process.

[0072] Optics are employed in embodiments to treat the output of thelaser. A phase shift mirror can be used to transform a laser beam withlinear polarization into a beam with circular polarization. To obtain acircularly polarized beam, a phase shift mirror is positioned with anincidence angle of 45 degrees and the laser beam output with a plane ofpolarization parallel to the laser base is rotated 45 degrees to theplane of incidence. The resulting circularly polarized beam of heatenergy is focused with a lens into a desired size on the outer surfaceof the seam. For example, a Melles Griot Zinc Selenide Positive Lenswith focal distance of 63.5 mm (2.5 inches) can be used as the imagelens. In the process of the present invention, all of the radiant energyemission from the carbon dioxide laser 103 progressively strikeslocalized sites encompassing the seam and regions of the imaging beltimmediately adjacent the seam to deliver instant heating followed byquick cooling as the belt 10 with the supporting cylindrical 90 istraversed by the beam of heat energy from the laser heating source.

[0073] Preferably, the raw laser heat energy beam emitted from a laserhas a circular cross section, but any other suitable cross sectionalshape can be used to raise the temperature of a localized site along theseam. The diameter of a raw beam emitted by a laser is normally constantalong the entire length of the beam. The thermal energy radiationemitted from a carbon dioxide laser is directed at the seam of the beltand the thermal energy radiation from the laser forms a localized site,such as a round spot, straddling the seam during traverse of the seam.The heated localized site, such as a round spot, on the surface of theseam preferably has an average width of between about 3 millimeters andabout 25 millimeters measured in a direction perpendicular to theimaginary centerline of the seam, depending upon the particulardimensions of the seam to be treated. For example, a Model Diamond 64sealed carbon dioxide laser from Coherent, Inc., has a circular raw heatenergy beam having a diameter of about 6 millimeters. This raw laserheat energy beam will form a heated localized site or spot having adiameter of about 6 millimeters on the belt seam. If desired, the 6millimeter spot size of the thermal energy striking the outer surface ofthe seam can be reduced for small seam area heating by masking theemitted raw laser heat energy beam using any suitable device, such as ametal template, to give a 3 millimeter to 6 millimeter heated localizedspot size measured in a direction perpendicular to the imaginarycenterline of the seam. Although the template can alter the heatedlocalized spot shape to any suitable and desired shape such as an oval,square, rectangle, hexagon, octagon and the like, a circular heatedlocalized site or spot is preferred. Moreover, where for example, thelaser heat energy beam has a diameter of about 6 millimeters and alarger heat spot is desired on the outer surface of the belt seam, thelaser beam can be defocused using any suitable device, such as a zincselenide lens between the laser beam source and the belt seam. Thus, byvarying the relative distances between the laser beam source, the lensand the belt seam, the 6 millimeter diameter laser beam can be defocusedto give a larger spot having a diameter greater than about 6 millimetersand preferably less than about 25 millimeters in diameter measured in adirection perpendicular to the imaginary centerline of the seam forstress release treatment of large seam areas. If a mask is employed tochange the shape of the raw laser heat energy beam or the defocused heatenergy beam to form a spot shape other than round, the preferred heatedlocalized site or spot size that straddles the seam has an averagediameter between about 3 millimeters and about 25 millimeters measuredin a direction perpendicular to the imaginary centerline of the seam.When the average diameter of the heated localized site measured in adirection perpendicular to the imaginary centerline of the seam is lessthan about 3 millimeters, the resulting stress release area is notenough to cover a seam region which has a width of about 3 millimetersfrom one side of the seam region to the other. When the average diameterof the heated spot is greater than about 25 millimeters, the stressrelease area exceeds the intended seam treatment region and extends intothe electrophotographic imaging zone of the belt normally used for imageformation.

[0074] Since the carbon dioxide laser delivers a constant diameter rawheat energy beam, the physical distance from the seam surface of theimaging belt to the laser is less important for the heat treatmentprocess of this invention, as long as the intended seam heat treatmentspot size is the same as the diameter of the raw laser beam or smallerthan the raw laser beam by using a masking template. the carbon dioxidelaser spot substantially instantaneously elevates the temperature ofpolymer material in only a small localized region or site of the imaginglayer of the imaging member above the glass transition temperature(T_(g)). Although the thermoplastic polymer material must be heated toat least the glass transition temperature thereof, such heated polymermaterial need be only in the upper portion of the seam area to achievethe seam treatment objectives of this invention. However, if desired,heating of the seam region completely through the thickness orcross-section thereof can be accomplished during heating of a localizedsite. Elevation of the temperature of only a small localized region orsite along the seam from one edge of the belt to the other to at leastthe glass transition temperature of the thermoplastic polymer materialis accomplished progressively as the heat energy beam traverses thewidth of the belt along the seam.

[0075] An alternative heat source, a variation of that shown in FIG. 7,employs an elongated focused IR emitting source that can include, forexample, an elongated halogen quartz tube coupled with a hemi-ellipsodalshaped cross-section elongated reflector. The elongated focused IRemitting source is positioned above the seam laminator strip and coversthe entire width of the imaging member 10. The elongated focused IRsource thus delivers an IR focused heating line to heat the entirelaminator strip 32 and seam 30 at once. The width of the focused IRheating line should cover the width of the laminate 34 of the laminatorstrip 32. The heated strip and seam can then be compressed, as with arolling wheel 108 (or a heated rolling wheel 115 according to that shownin FIG. 9), while the belt 10 is belt down over the arcuate convexsurface of tube 90, to complete the seam overcoating/laminationtreatment. Such a focused IR heating line can also be used inembodiments according to the process and apparatus of FIG. 6 where anexternally-heated or cold compression rolling wheel 150 is used, whilebelt 10 is held down over the surface of flat support 148.

[0076]FIG. 9 illustrates another alternative embodiment of seamovercoating/lamination process and apparatus similar to that shown inFIG. 7. A single, internally-heated compression wheel 115 is employed toheat and compress the seam 30 of a belt 10 situated and held down withvacuum on an elongated support tube 90. The peripheral surface of wheel115 has an arcuate concave cross section having a curvature whichcorresponds to or is slightly larger than the curvature of the arcuateconvex surface of the elongated surface of the upper half of supporttube 90. This peripheral wheel surface should be maintained at atemperature sufficient to raise the temperature of the thermoplasticmaterial in at least the upper half of the belt seam to its glasstransition temperature T_(g). The peripheral surface of wheel 115 alsopreferably has a thin coating surface of abhesive material, such as afluoropolymer, such as Teflon, and the like to prevent imaging layermaterial from adhering to the wheel surface during the seam treatmentprocess. The heated compression wheel 115 is preferably metallic with asmooth peripheral surface. Heating of the wheel can be accomplished byany suitable device such as, for example, by an electromagnetic heatingmechanism 116 to give the desired temperature when wheel 115 traversesthe width of belt 10 along on the seam 30. Alternatively, any othersuitable device, such as a resistance wire heating system 117 can beemployed to heat compression wheel 115. Where the resistance wire ispart of the wheel, any suitable electrical connection such as slip rings118 can be used to provide electrical energy to the resistance wires.Sufficient heat energy should be supplied to wheel 115 to adequatelyheat the peripheral surface thereof. Preferably, the hot rotatablecompression wheel 115 is not reciprocated and the support tube 90carrying belt 10 is moved during the seam treatment. However, ifdesired, the support tube and belt can be stationary and the wheelreciprocated or both can be reciprocated to achieve relative motion witheach other.

[0077] Thus, the process and apparatus of embodiments as shown in theexamples described above produce a flexible imaging member in which theseam has a protective overcoating substantially free of protrusions, asmooth surface profile, and that exhibits good physical continuity.Additionally, the seam area produced by embodiments has reduced seamarea thickness and enjoys reduced fatigue induced bending seam stresscracking under dynamic belt flexing conditions over the rollers a beltsupport module during imaging machine operation. Furthermore, treatingaccording to embodiments can substantially enhance imaging memberproduction yield, effectively reducing the belt unit manufacturing cost.Because successful implementation of embodiments greatly reduces ofsubstantially eliminates the need of labor-intensive and time-consumingmanual seam inspection procedures, embodiments also effectively increaseproduction belt yield by recovery of those belts that are otherwise lostas rejects due to the presence of seam protrusions. Thus, embodimentsdeliver a seam configuration with significantly improved qualities,better physical/mechanical attributes, such as smoother surface profile,absence of protrusion spots, thinner cross-section thickness, and littleor no physical discontinuity to enhance cleaning blade performance andsuppress the premature onset of fatigue induced seamcracking/delamination problem during extended electrophotographicimaging and cleaning processes.

[0078] It should be noted that, though embodiments use a treatmentarticle or strip with the thermoplastic polymer film on acarrier/support substrate, such as that shown in FIG. 4, the presentinvention can be performed with a treatment article or strip including asingle layer of thermoplastic polymer with no carrier/support substrate.A number of examples are set forth hereinbelow and are illustrative ofdifferent compositions and conditions that can be used in practicingembodiments. All proportions are by weight unless otherwise indicated,are exemplary in nature, and are not limiting to the invention. It willbe apparent that the invention can be practiced with many types ofcompositions and can have many different uses in accordance with thedisclosure above and as pointed out hereinafter.

EXAMPLE I Belt Preparation

[0079] An electrophotographic imaging member web was prepared byproviding a roll of titanium-coated, biaxially-oriented thermoplasticpolyester substrate. The substrate comprised PET, Melinex (availablefrom ICI Americas, Inc.) and had a thickness of 3 mils (76.2micrometers). A blocking layer with a dry thickness of 0.05 micrometerwas formed on the substrate, on which an adhesive interface layer wasthen prepared with a dry thickness of 0.07 micrometer. The adhesiveinterface layer was thereafter coated with a photogenerating layer witha dry thickness of 2.0 micrometers. However, a strip about 3 mm widealong one edge of the coating web, having the blocking layer andadhesive layer, was deliberately left uncoated by any of thephotogenerating layer material to facilitate adequate electrical contactwith the ground strip layer that is applied later. Next, a chargetransport layer and a ground strip layer were applied by co-extrusion ofthe coating materials. The uncoated portion of the adhesive layer wasincluded in the application of the ground strip layer. Finally, ananti-curl coating was applied to the rear surface (side opposite thephotogenerator layer and charge transport layer) of theelectrophotographic imaging member web to produce a dried coating layerhaving a thickness of 13.5 micrometers.

[0080] The charge transport layer was prepared by introducing into anamber glass bottle in a weight ratio of 1:1 (or 50% wt of each)N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine andMakrolon 5705, a Bisphenol A polycarbonate thermoplastic having amolecular weight of about 120,000 commercially available fromFarbensabricken Bayer A.G. The resulting mixture was dissolved to give15 percent by weight solid in methylene chloride. This solution wasapplied on the photogenerator layer by extrusion to form a coating whichupon drying gave a thickness of 24 micrometers.

[0081] The prepared electrophotographic imaging member web had a widthof 353 millimeters and was cut to provide five rectangular sheets each559.5 millimeters in length for flexible imaging member seamingoperation. The opposite ends of each imaging member were overlapped 1 mmand joined by an ultrasonic energy seam welding process using a 40 Khzhorn frequency to form a seamed electrophotographic imaging member,having a top seam splashing surface morphology 74 and displaying aphysical discontinuity step 72 with a junction point 76 according to theillustration in FIG. 2. Four of the five seamed belts were ready to beused for invention seam overcoationg/lamination processing while one ofthe remaining unprocessed seamed belt was used to serve as a control.

EXAMPLE II Treatment Article Preparation and Application No Substrate

[0082] Six thermoplastic polymercoating solutions were prepared bydissolving Makrolon 5705 polycarbonate with varying amount of chargetransport compoundN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine inmethylene chloride. The prepared solutions were each applied over areleasing substrate and dried at 257° F. (125° C.) in an air circulatingoven for 5 minutes to rid the solvent and then removed from the releasesubstrates to give thermoplastic polymer layers containing 0% wt, 10%wt, 20% wt, 30% wt, 40% wt, and 50% wt charge transport compound in eachrespective 25 micrometer thick layer. The thermoplastic polymer layerswere each analyzed for glass transition temperature, T_(g), usingdifferential scanning calorimetric method. The results obtained, listedin the table below, showed that the addition of charge transportcompound to the Makrolon could provide successive suppression of theT_(g) of the resulting polymer layer: POLYMER LAYER T_(g) (° C.) 0%wt15610% wt13520% wt12030% wt10440% wt9150% wt84A 5 mm width strip wascut from the thermoplastic polymer layer containing 50% by weight chargetransport compound (essentially identical to the charge transport layerof the electrophotographic imaging member of Example I) and placed overthe top seam splash 68 (refer to seam morphology description in FIG. 2)of one welded electrophotographic imaging member of Example I, which wasvacuum held down, to overcoat/laminate the seam region by heat andcompression processing as that in FIG. 5. The compression pressureexerted by the hot compression bar was approximately 200 lbs/in² andwith a temperature of about 130° C. to effect the seamovercoating/lamination outcome.

[0083] Since the processing was carried out at a temperature 46° C.above the T_(g), the overcoat laminate became compressible as well asmalleable under the applied pressure to readily fuse onto the seam andfill-up the seam step junction 76.

EXAMPLE III Treatment Article Prepration and Application Substrate

[0084] A coating solution, prepared by dissolving 10 grams of Makrolonin 90 grams of solvent mixture consisting of 90 parts of methylenechloride and 10 parts of toluene, was applied to a 3-mil thick,biaxially-oriented PET substrate by hand coating using a Birdapplicator. The coated wet Makrolon layer was allowed to dry under roomambient conditions for 15 hours to produce a 35-micrometer thick solidpolymer layer containing 60% by weight Makrolon and approximately 40% byweight toluene, with only a small amount of residual methylene chloridesince toluene was much less volatile than methylene chloride. Theresulting coating layer over PET substrate was cut to give an 8 mm widthstrip. The coating layer in this 8 mm strip was cut at both sides,through only the Makrolon layer not the PET, to remove 2 mm of Makroloncoating layer from each side to create a laminator strip 32, like thatillustrated in FIG. 4, which consists of a 4 mm width thermoplasticpolymer laminate 34 adhered onto an 8 mm wide flexible PET carriersubstrate 36.

[0085] The fabricated laminator strip 32 was positioned over the seam ofthe second welded electrophotographic imaging member of Example I andthen subjected to the inventive seam overcoating/lamination processing,carried out with the same procedures and apparatus as described inExample II. Since the laminate strip 34 was loosely adhered to the PETcarrier substrate 36 (only about 6 grams/cm 180° peel strength), it waseasily removed from the seam overcoat after completion of theheat/compression application. The resulting overcoated seam had beenfound to obtain about equivalent physical and morphological attributeimprovements seen in the treated seam of Example II.

EXAMPLE IV Treatment Article Preparation & Application Solution ofExample II on Substrate; IR Lamp and Wheel on Tube

[0086] A laminator strip 32 was prepared, using a coating solutionaccording to Example II and a 3-mil thick biaxially oriented PETsubstrate, according to the procedures described in Example III, to givea 25-micrometer thick polymer laminate 34, containing 70% by weightMakrolon and 30% by weight charge transport compound, over PET carriersubstrate 36. The surface of laminate 34 of the prepared laminator strip32 was first brushed (using a small soft paint brush) with small amountof methylene chloride to moisten the surface and thereby promote someadhesion to the seam region surface for ease of anchoring the laminatorstrip 32 directly onto the seam of the third welded electrophotographicimaging member of Example I, which was held down over a 2-inch diametertube 90 as illustrated in FIG. 7. The overcoating/lamination processingused an IR heat source 103 to provide a focused, 8 mm diameter hot spotfor localized heating of the laminator strip 32 to a temperature of 120°C. The hot spot was followed with a free rotating compression wheel 108to generate an 8 lbs/in compression line for effective seamovercoating/lamination result.

[0087] The heating and compression procedures to achieve the inventionseam overcoating/lamination result were carried out according toembodiments such as that illustrated in FIG. 7 and given in thepreceding text of this specification. Since the laminate 34 was looselyadhered to the PET carrier substrate 36, the PET was readily peeled offfrom the overcoated seam after the processing.

EXAMPLE V Treatment Article Preparation and Application TreatmentArticle of Example IV, IR Laser and Wheel on Tube

[0088] A laminator strip 32 was again prepared, in exact same mannersdescribed in Example IV, to give a. laminate 34 having 25 micrometers inthickness and containing 30% by weight charge transport compound overPET carrier substrate 36.

[0089] To effect invention seam treatment processing, the fourth weldedelectrophotographic imaging member 10 of Example I was suspended (asshown in the illustration of FIG. 7) over a horizontally movablecantilevered supporting aluminum tube 90, having a 2-inch (5.08centimeters) diameter, a wall thickness of about 0.25 inch (6.35millimeters), and an anodized outer surface, with the welded seam 30parked directly along the top (i.e. 12 o”clock position) of the supporttube 10 and being parallel to the axis of the tube. The tube 10contained a pair of slots 10, with one slot at the 9 o”clock positionand the other at the 3 o”clock position. Each slot extended along thelength of the imaging member width and was 2 millimeters wide. The freeend of the tube 10 was sealed by a cap and the supported end wasconnected to a flexible hose leading through a valve to a vacuum source.The vacuum source was maintained at a pressure of about 40 mm Hg. Thebelt in the seam area was held down against the upper arcuate convexsurface of the supporting tube when the valve to the vacuum source wasopened so that the seam area conformed to the shape of the upper surfaceof the tube. The laminator strip 32, having the surface of the laminate34 moistened with methylene chloride was placed directly over the seamgive some adhesion hold down onto the seam region for ease of carryingout the heat/compression seam lamination process. The temperature of alocalized circular spot, about 8 mm in diameter, of the laminator strip32 and the respective covering seam region was raised to about 120° C.using a sealed carbon dioxide laser heating source 103 (Model Diamond64, available from Coherent, Inc.) instead of the focused IR of ExampleIV. The laser heat source 103 had an adjacent trailing free rotatingcompression wheel attachment, as shown in FIG. 8, which was adjustableto deliver an about 8 lbs/cm compresion line over the heat spot byspring 110, to effect the heat/compression process.

[0090] This invention seam treatment processing was then carried outaccording to the schematic illustration of FIG. 7. The carbon dioxidelaser heating source had a 150 wattage power capability, but for thepurpose of present seam treatment process, it was adjusted to deliver anenergy output of only about 5.6 watts at an 8 millimeter diameter of rawlaser beam spot. an infrared sensing camera was employed to adjust laserdelivery of 150 Hz, 50 microsecond pulse duration, and a seam traversingspeed of 2 in/s (5.08 cm/s) to ensure that the heat spot on laminatorstrip for seam treatment temperature reached 120° C. A spot temperatureof 120° C. was sufficient to soften the laminate 34 and the chargetransport layer beneath the laminate 34 for effectual application of theovercoating laminate to smooth out surface profile, fill the seam splashjunction 76 to thereby eliminate the physical discontinuity, and yieldseam stress-release result. The laser heat source emitted a dominantradiant wavelength of 10.64 micrometers and formed a substantiallycircular laser spot of about 8 mm in diameter incident over andstraddling the laminator strip and seam area to provide instant heatingresult in the localized site to effect such heating progressing alongthe length of the seam, as the support tube 90 with the held down belt10 were moved under the laser heat source/compression wheel assembly ata traversal speed of 2 in/s (5.08 cm/ss) and exerting about 20 pounds ofrotating wheel compression force by the spring 110 to yield a 4 mm linecontact over the laminator strip and the covering seam region;accordingly, the rotating wheel generated an compression line force ofabout 8 lb/cm linear width. The entire seam heat/compression andovercoating/lamination processing carried out for each imaging memberwas completed in about seven seconds.

EXAMPLE VI

[0091] The invention seam overcoating/lamination processing carried outfor the seamed electrophotographic imaging member belts described inExamples II to V was seen to give overcoat laminate that was stronglybonded to the welded seam region, since the laminate used wasessentially made of the same materials and chemical components of theseam. Therefore, the end result of the seam overcoating/lamination wasthat the laminate was fused onto the seam area and became an integralpart of the seam, which eliminated the physical discontinuity to displaya tapering surface topology without the seam splash junction 76. Furtherseam surface roughness analysis of these seamed belts before and aftertreatment, using a Wyko Gauge surface analyzer, showed that the originalseam splash surface roughness was significantly reduced from an averagehigh Ra value of 6.3 to a low value of 1.6. The inventive treatmentprocess was also found to produce a slight overall reduction in seamarea thickness of up to about 10 percent.

[0092] The control electrophotographic imaging member of Example I andthe four seam overcoated electrophotographic imaging members obtainedthrough the treatment process of the present invention described byExamples II to V were each dynamically cycled and print tested in axerographic machine, having a belt support module comprising a 25.24 mmdiameter drive roller, a 25.24 mm diameter stripper roller, and a 29.48mm diameter tension roller to exert on each belt a tension of 1.1 poundsper inch. The belt cycling speed was set at 65 prints per minute.

[0093] The control imaging member of Example I, having no seam overcoatlaminate, was cyclic tested to only about 56,000 prints and terminatedfor the reason of developing onset of seam cracking/delaminationproblem.

[0094] When the very same belt cycling procedure was repeated with eachof the imaging members through the process of the present invention,neither seam failure nor notable ripple appearance in the image zoneswere observed after completion of 500,000 prints of belt cyclic testing.Further, minimal cleaning blade wear was observed after completion of500,000 prints of belt cyclic testing.

[0095] In recapitulation, the seam overcoating/lamination process of thepresent invention resolves seam cracking/delamination problems, providesa very short treatment processing cycle time, substantially eliminatesseam splash junction physical discontinuity, substantially prevents theappearance of ripples in the imaging zones adjacent to the seam heattreatment area, provides smoother surface profiles, producesdimensionally stable imaging members, suppresses cleaning blade wear,and yields a processed seam substantially free of high protrusion spotsto thereby reduce seamed imaging member rejection rates, which increasesimaging member production yield.

[0096] Although the invention has been described with reference tospecific exemplary embodiments, it is not intended to be limitedthereto. Rather, those having ordinary skill in the art will recognizethat variations and modifications may be made therein which are withinthe spirit of the invention and within the scope of the claims.

1. A flexible imaging member seam treatment article preparation methodcomprising: providing a flexible substrate comprising ahigh-temperature-resistant material; coating a surface of the flexiblesubstrate with a solution including at least one thermoplastic polymercomponent; and drying the coated surface to form a film of the at leastone polymer component on the coated surface.
 2. The method of claim 1further comprising cutting the coated flexible substrate into at leastone strip sized to cover the seam.
 3. The method of claim 1 whereinproviding a flexible substrate comprises providing a web of ahigh-temperature-resistant material and the method further comprisesforming a roll from the dried, coated flexible substrate.
 4. The methodof claim 1 wherein providing a flexible substrate comprises providing ametallic substrate.
 5. The method of claim 1 wherein providing aflexible substrate comprises providing ahigh-glass-transistion-temperature flexible polymeric film.
 6. Themethod of claim 5 wherein providing a high-glass-transition-temperatureflexible polymeric film comprises providing a biaxially-oriented PETfilm.
 7. The method of claim 1 wherein coating a surface of the flexiblesubstrate comprises providing a solution including a charge transportcompound.
 8. The method of claim 7 wherein providing a solution furthercomprises dissolving a polycarbonate and the charge transport compoundin an organic solvent.
 9. The method of claim 8 wherein thepolycarbonate includes Makrolon.
 10. A belt seam treatment strippreparation method comprising: dissolving a thermoplastic polymer into asolvent; applying the dissolved thermoplastic polymer to a surface of ahigh-temperature-resistant flexible substrate; and eliminating thesolvent to form a thermoplastic polymer film on the surface of thesubstrate.
 11. The method of claim 10 wherein dissolving a thermoplasticpolymer into a solvent comprises providing an organic solvent.
 12. Themethod of claim 10 wherein dissolving a thermoplastic polymer comprisesproviding at least one of a granular and a powder of a film-formingthermoplastic polymer.
 13. The method of claim 10 wherein eliminatingthe solvent comprises air drying the coated substrate.
 14. The method ofclaim 10 wherein eliminating the solvent comprises baking the coatedsubstrate.
 15. The method of claim 10 wherein applying the dissolvedthermoplastic polymer comprises providing a web ofhigh-temperature-resistant flexible substrate.
 16. The method of claim10 wherein applying the dissolved thermoplastic polymer comprisesproviding a high-glass-transition-temperature flexible polymersubstrate.
 17. The method of claim 16 wherein providing ahigh-glass-transition-temperature flexible polymer substrate includesproviding a biaxially-oriented PET film.
 18. The method of claim 10wherein applying the dissolved thermoplastic polymer comprises providinga metallic film.
 19. The method of claim 10 wherein dissolving athermoplastic polymer comprises providing a charge transport compound.20. The method of claim 19 wherein providing a charge transport compoundfurther comprises providingN,Nζ-diphenyl-N,Nζ-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine as acharge transport compound.
 21. The method of claim 20 wherein thedissolved thermoplastic polymer comprises a bisphenol-A polycarbonate ofMakrolon and includes the charge transport compound.
 22. A flexibleimaging belt seam treatment article comprising ahigh-temperature-resistant flexible substrate supporting a thermoplasticpolymer film deposited thereon by dissolution of a film-formingthermoplastic polymer in a carrier solvent, application of a resultingsolution to the flexible substrate, and elimination of the carriersolvent.
 23. The article of claim 22 wherein thehigh-temperature-resistant flexible substrate comprises a flexiblemetallic film.
 24. The article of claim 22 wherein thehigh-temperature-resistant flexible substrate comprises ahigh-glass-transition-temperature polymer sheet.
 25. The article ofclaim 22 wherein the deposited thermoplastic polymer film comprises abisphenol-A polycarbonate and a charge transport compound.
 26. Thearticle of claim 25 wherein the bisphenol-A polycarbonate is Makrolonand the charge transport compound isN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine.